Fuel splashplate for microturbine combustor

ABSTRACT

A splashplate dish or disc shaped having a contoured face is inserted in and recessed from the top of the air tube feeding the combustor of a microturbine with a mixture of air and fuel. The splashplate permits the use of a single orifice fuel nozzle or injector to replace a multi orifice injector. The splashplate includes contoured segments circumferentially disposed around the face of the splashplate for splitting the fuel into discrete streams for mixing with the air admitted into the air tube. In one embodiment the splashplate includes radial slots circumferentially spaced around the face of the splashplate for directing the fuel directly into the air tube through the slots. In another embodiment a dimple or depression is located centrally of the splashplate where the fuel impinges before being dispersed in the plurality of streams. Attachment means are provided for centering and recessing the splashplate in the air tube.

TECHNICAL FIELD

[0001] This invention relates to fuel nozzles for gas turbine enginesand particularly to the fuel nozzle/air tube for the combustor of amicroturbine.

BACKGROUND OF THE INVENTION

[0002] The microturbine is essentially a miniaturized gas turbine enginetypically utilized for powering electrical generators. In certainconfigurations, the turbine and compressor are attached back-to-back onone end of a shaft that is common to the shaft connecting the armatureof the electrical generator. Fuel and relatively hot pressurized airdischarging from the compressor and recuperator are fed to an annularcombustor where they are combined and combusted to further heat andaccelerate the engine's working medium for powering the turbine. Theengine working medium is adiabatically expanded in the turbine forextracting energy which, in turn, is utilized for rotating thecompressor and armature. The working medium after leaving the turbine isdirected to the recuperator where it is placed in indirect heat exchangewith the compressor discharge air prior to being admitted into thecombustor. The turbine exhaust is ultimately discharged from therecuperator. For further details of the microturbine reference should bemade to co-pending patent application Ser. No. 09/934,640 filed on Aug.22, 2001 by William R. Ryan entitled RECUPERATOR FOR USE WITHTURBINE/TURBO-ALTERNATOR, published and U.S. Pat. No. 6,314,717 grantedto Teets et al on Nov. 13, 2001 entitled ELECTRICITY GENERATING SYSTEMHAVING AN ANNULAR COMBUSTOR both of which are commonly assigned to theassignee of this patent application, and both being incorporated byreference herein. Also, for more details of this invention referenceshould also be made to the microturbines manufactured by the assignee,Elliott Energy Systems, Inc., of Stuart, Fla. and, particularly of thetypes exemplified by Model Number TA-80.

[0003] A continuing effort is being made by scientist and engineers toimprove on the efficiency of the microturbine engine from a standpointof the quality of the emissions exhausting from the engine, theefficiency of the engine, the cost of manufacturing, and the maintenancethereof. To this end, it is contemplated that the burning efficiency,the quality of exhaust and costs can be improved by providing asplashplate judiciously located in the air tube associated with the fuelinjector of the combustor. In accordance with this invention, thesplashplate permits the use of a single orifice fuel injector and hence,eliminates the multiple orifices fuel injectors. Since the area of theorifice of the single orifice injector is larger than the area of theorifice of the multiple orifice injector, the likelihood of cloggingowing to adhesion of foreign matter at the discharge orifice isminimized, if not eliminated. The use of the splashplate that createsthe discrete streams of fuel for enhanced mixing affords the benefit ofimproved burning efficiency and lower maintenance. Because thesplashplate of this invention replaces the multiple orifices in the fuelnozzle with a single orifice, lower manufacturing costs are achievablein addition to avoiding, if not eliminating, clogging of the dischargeorifice. The invention contemplates shaping the aft end of thesplashplate to avoid recirculation of the fuel/air mixture atinappropriate locations and hence, avoiding flaming at undesirablelocations.

SUMMARY OF THE INVENTION

[0004] An object of this invention is to provide for the fuel injectionsystem of the combustor of a microturbine engine a splashplatejudiciously located in the air tube.

[0005] A feature of this invention is the provision of the splashplateas described mounted in the air tube wherein the face of the splashplateis formed in concaved/convex segments circumferentially formed thereinto discretely form fuel streams to effectively mix with the air in theair tube.

[0006] Another feature of this invention is the provision of thesplashplate as described wherein the face of the splashplate is formedwith a central depression and the contoured segments circumferentiallyradiate therefrom.

[0007] Another feature of this invention is the configuration of the aftend of the splashplate to minimize or eliminate the occurrence ofrecirculation zones immediately downstream thereof.

[0008] Another feature of this invention is a splashplate as describedincluding a plurality of radially extending slots circumferentiallyspaced therein for admitting the fuel impinging on the splashplate tomix with the air in the air tube.

[0009] Another feature of this invention is the attachment and centeringmechanism for the splashplate of this invention wherein in oneembodiment the attachment interconnects the fuel nozzle and splashplatefor centering the splashplate relative to the fuel nozzle.

[0010] The foregoing and other features of the present invention willbecome more apparent from the following description and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view of the annular combustion liner andthe a partial showing of the fuel manifold of this invention with thesplashplate out of view;

[0012]FIG. 2 is an end plan view illustrating the splashplate of thisinvention mounted to the air tube;

[0013]FIG. 3 is a view partly in schematic and partly in section takenalong lines 3-3 of FIG. 2;

[0014]FIG. 4 is a partial view in perspective illustrating anotherembodiment of this invention;

[0015]FIG. 5 is a partial view in perspective illustrating anotherembodiment of this invention;

[0016]FIG. 6 is a partial view in perspective illustrating anotherembodiment of this invention;

[0017]FIG. 7 is a view in section taken along lines 7-7 of FIG. 6;

[0018]FIG. 8 is a sectional view illustrating a modification of thisinvention with a configured aft section for preventing localizedrecirculation; and

[0019]FIG. 9 is a schematic view illustrating an option for attachingthe splashplate.

[0020] These figures merely serve to further clarify and illustrate thepresent invention and are not intended to limit the scope thereof.

DETAILED DESCRIPTION OF THE INVENTION

[0021] While splashplates and buffer zones have been utilized in rocketengines and in gas turbine engines, the use of a splashplate in an airtube is an entirely different application for splashplates. In thisinvention, the splashplate is utilized to eliminate the multi-port fuelinjectors and replace them with a single hole fuel injector. Since thesame fuel flow is required in both the single and multi-holed injector,the cross sectional area of the single hole is substantially equal tothe total cross sectional areas of the multi-port injectors, thusminimizing, if not eliminating, the potential of clogging the port.Moreover, the splashplate of this invention is an alternative method ofassuring the creation of smaller particle sizes for enhanced mixing thatis necessary for efficient burning. Heretofore, the fuel injector forthe combustor of a microturbine utilized three holes so as to obtain thedesired particle sizes in the streams of fuel. In the microturbine thatutilizes gaseous fuel, the injector included three holes to producethree streams of gaseous fuel that is injected into the combustion zone.Obviously, the manufacturing costs for making a three ported injector issignificantly more expensive than a single ported injector. Theinvention contemplates the use of liquid fuel as well as gaseous fuel.

[0022] To best appreciate this invention, reference will be made to FIG.1 which illustrates the annular combustion liner generally illustratedby reference numeral 10 having an outer liner 12 and an inner liner 14that is closed on one end at 16 and is opened on the opposite end andthe outer and inner liner define an annular combustor passage wherefuel/air (fuel can be either liquid or gas) is ignited and combusted togenerate the working fluid for the engine. The working fluid dischargesfrom the aft end 18 of the combustor 20 and flows into the turbine (notshown) for generating the power of the engine. A plurality of fuelinjectors 20 fluidly connected to the fuel manifold 22 which isconnected to a source of fuel (not shown) feed the circumferentiallyspaced primary air tubes 24. This particular combustor liner includes adam defining the primary and secondary combustion zones and a pluralityof vanes 26 connected to the dam for admitting air into the combustionzone and a plurality of circumferentially spaced combustion or dilutionholes 28 for admitting air into the combustion zone. These elements arewell known and do not constitute this invention. This invention modifiesthese existing components by including the splashplate that will bedescribed immediately hereinbelow. For further details of themicroturbine and the annular combustion liner reference should be madeto U.S. patent application Ser. No. 06/165,876 filed on Jun. 10, 2002 byWilliam F. Beacom entitled Vane and Method of Construction Thereof andcommonly assigned to this assignee.

[0023]FIGS. 2 through 5 disclose a plurality of splashplates havingdifferent configuration and it is to be understood by those skilled inthis technology that configurations can take many forms so long as thefuel injected thereon is divided into separate streams that dischargeinto the air tube. In each of the embodiments of the splashplatesdepicted in FIGS. 2 through 5, the splashplates 30, 32 and 34,respectively, are stamped out of sheet metal and are generally circularin shape whose diameter is less than the inside diameter of the air tube36. (Similar elements have the same reference numerals in all of theFigs.). The fuel injector 38 directs fuel to impinge on the centralportion of the splashplates 30, 32 and 34, respectively. In each of thesplashplates the fuel is split up into different streams formed aroundthe circumference of the respective splashplate and discharge into theair tube and mixed with the air flowing into the air tube directly intothe combustion zone. The splashplates 30, 32 and 34 are configureddifferently and the face of each of the splashplates are wave-shaped(concave and convex) to define equal segments around the circumferencefor defining troughs or channels for defining separate streams of fuel.In FIG. 2 the splashplate 30 included a central depression or recesssurface 40 and is formed adjacent to the plurality of circumferentiallyspaced troughs 42. The splashplate depicted in FIG. 4 includes a raisedcenter portion 44 and similarly to FIG. 2 includes a plurality ofcircumferentially spaced segments that include troughs 46. FIG. 5 isconfigured similar to FIG. 4 where the raised central portion 48 isdimpled to define a depressed center 50 and the troughs 52 radiate offof this depressed center 50. The splashplates 30, 32 and 34 are mountedin place by a plurality (three in this instance) of inwardly bent andcircumferentially spaced tabs 54 that fit into a complementary recess 56formed on the fore edge 58 of the air tube 36 and secured thereby bysuitable welds. It will be appreciated from the foregoing that the tabs54 are angled so as to recess the respective splashplates into the airtube. Hence, the fuel impinging on the splashplate will notinadvertently spill overboard rather than flow directly into thecombustion chamber.

[0024] The splashplate 60 depicted in FIG. 6 is formed from a metallicblank and includes a plurality of slots 62 circumferentially spaced inthe segments of the circle and radiate from a central depression 64. Themulti-streams of fuel formed by virtue of the impingement on thesplashplate flow into the slots 62 where it mixes with the air in theair tube prior to being admitted into the combustion chamber. The aftend 61 of splashplate 60 is dome shaped and this shape serves to preventthe fuel/air mixture forming a localized recirculation zone adjacent tothe aft end of the splashplate. Spaced tabs 63 (three are shown) extendfrom the periphery of the splashplate 60 and fit into complementaryslots 69 formed on the top edge 65 of the air tube 67 for supporting thesplashplate 60. The tabs 63 may be affixed by a suitable means such asweld or braze. This configuration as well as the one to be described inconnection with FIG. 8 can be applied to all the other configuredsplashplates where it is found that localized recirculation is aproblem. FIG. 8 is included to show that other configurations such asthe cone shape aft end 71 can be employed with any of the splashplates.

[0025] The structure in FIG. 9 illustrates the option of attaching thesplashplate to the fuel nozzle 72. In this instance the splashplate 70includes three elongated brackets 76 (two being shown) that are weldedto the outer periphery of the splashplate 70 at equal circumferentialspaces and are bent over the fore shoulder 74 of the fuel nozzle 72 andare welded or attached by any other suitable means to the body of nozzle72. This attachment means assures that the splashplate is oriented withrespect to the discharge port or orifice of the fuel nozzle and that itis centered relative thereto and the air tube. Obviously, the fuelnozzle or injector needs to be removed before removing the liner when itis necessary to repair or overhaul the combustor.

[0026] What has been shown by this invention is a relatively inexpensiveway to enhance the fuel delivery to a combustion section by eliminatingthe heretofore triple orifice injector and replacing it with a singleorifice injector. The wavy or grooved shape of the various configuredsplashplates divides the fuel into multiple smaller streams foreffectively mixing with the air in the air tubes before delivery intothe combustion zone. Also, effective means are disclosed to eliminate orprevent recirculation zones localizing adjacent to the aft end of thesplashplate. The invention is characterized by efficacious mixing whileeliminating the more expensive multi-orifice fuel injector.

[0027] Although this invention has been shown and described with respectto detailed embodiments thereof, it will be appreciated and understoodby those skilled in the art that various changes in form and detailthereof may be made without departing from the spirit and scope of theclaimed invention.

It is claimed:
 1. For the combustor of a microturbine engine including aplurality of air tubes feeding air into the combustion zone of thecombustor, at least one splashplate mounted in one of said air tubes,said splashplate being circular in shape, at least one fuel nozzle forfeeding fuel into said one air tube, said splashplate having aperipheral edge that is smaller in diameter than the diameter of saidone air tube, said fuel nozzle directing the flow of fuel dischargingtherefrom to impinge on said splashplate, said splashplate having aforward facing face defining a particular configuration whereby the fuelimpinging on said splashplate is broken up into discrete streams of fuelby said particular configuration on the face of said splashplate and fedinto said one air tube to mix with the air in said one air tube prior tobeing admitted into the combustion zone.
 2. For the combustor of amicroturbine engine as claimed in claim 1 including a plurality of tabshaving one end attached to said splashplate and another end attached tosaid one air tube supporting said splashplate in said one air tube andrecessed from the end of said one air tube.
 3. For the combustor of amicroturbine engine as claimed in claim 1 including a bracketinterconnecting said splashplate and said fuel nozzle for supportingsaid splashplate in said one air tube and said splashplate beingrecessed in said one air tube whereby said splashplate is centeredrelative to the fuel discharging from said fuel nozzle.
 4. For thecombustor of a microturbine engine as claimed in claim 1 including aplurality of circumferentially spaced radial slots formed in said onesplashplate.
 5. A plurality of circular shaped splashplates for thecombustor of a microturbine engine in combination with a plurality ofair tubes circumferentially mounted about the combustor for feeding airinto the combustion zone of the combustor, each of said splashplatesmounted in each of said air tubes, a plurality of fuel nozzlescomplementing the number of air tubes for feeding fuel into saidplurality of air tubes, each of said splashplates having a peripheraledge that is smaller in diameter than the diameter of said air tube,each of said splashplates having a forward facing face defining aparticular configuration whereby the fuel discharging from each of saidfuel nozzles impinges on each of said splashplates and is broken up intodiscrete streams of fuel by said particular configuration on the face ofeach of said splashplates and fed into each of said air tubes to mixwith the air therein prior to being admitted into the combustion zone.6. A plurality of splashplates for the combustor of a microturbineengine as claimed in claim 5 wherein said forward facing face includes aplurality of circumferential segments extending from the center of thesplashplate toward the peripheral edge of the splashplate.
 7. Aplurality of splashplates for the combustor of a microturbine engine asclaimed in claim 6 wherein said segments are concave relative to theforward facing face.
 8. A plurality of splashplates for the combustor ofa microturbine engine as claimed in claim 6 wherein said segments areconvex relative to the forward facing face.
 9. A plurality ofsplashplates for the combustor of a microturbine engine as claimed inclaim 7 including a recess centered in said forward facing face.
 10. Aplurality of splashplates for the combustor of a microturbine engine asclaimed in claim 8 including a recess centered in said forward facingface.
 11. A plurality of splashplates for the combustor of amicroturbine engine as claimed in claim 10 including a radial slotformed in each of said segments for flowing fuel through said radialslot into said air tube to mix with the air therein.
 12. A plurality ofsplashplates for the combustor of a microturbine engine as claimed inclaim 5 wherein said fuel nozzle consists essentially of a single fueldischarging orifice.
 13. A plurality of splashplates for the combustorof a microturbine engine as claimed in claim 5 including spaced tabsmounted on each of said splashplates and attached to each of saidcomplementary air tubes for supporting each of the splashplates in eachof said air tubes whereby said splashplates are recessed in said airtubes to prevent the fuel impinging on said splashplates from spillingout of the complementary air tube.
 14. A plurality of splashplates forthe combustor of a microturbine engine as claimed in claim 5 including abracket interconnecting each of said splashplates with each of said fuelnozzles for supporting the complementary splashplate in saidcomplementary air tube and each splashplate being recessed from the topof the complementary air tube to prevent the fuel impinging on saidsplashplates from spilling out of the complementary air tube.
 15. Incombination, a plurality of fuel nozzles, a complementary number of airtubes in fluid communication therewith and a complementary number ofcircular shaped splashplates for the combustor of a microturbine engine,each of said plurality of fuel nozzles consisting essentially of asingle fuel discharging orifice, each of said air tubescircumferentially mounted about the combustor for feeding air into thecombustion zone of the combustor, each of said splashplates mounted ineach of said air tubes, each fuel nozzle of said plurality of fuelnozzles feeding fuel into a complementary air tube, each of saidsplashplates having a peripheral edge that is smaller in diameter thanthe diameter of said complementary air tube, each of said splashplatesbeing circular in shape and having a forward facing face defining aparticular configuration whereby the fuel discharging from each of saidfuel nozzles impinges on each of said splashplates and is broken up intodiscrete streams of fuel by said particular configuration on the face ofeach of said splashplates and fed into each of said air tubes to mixwith the air therein prior to being admitted into the combustion zone.16. The combination as claimed in claim 15 wherein said forward facingface includes a plurality of circumferential segments extending from thecenter of the splashplate toward the peripheral edge of the splashplate.17. The combination as claimed in claim 16 wherein said segments areconcave relative to the forward facing face.
 18. The combination asclaimed in claim 16 wherein said segments are convex relative to theforward facing face.
 19. The combination as claimed in claim 17including a recess centered in said forward facing face.
 20. Thecombination as claimed in claim 18 including a recess centered in saidforward facing face.
 21. The combination as claimed in claim 16including a radial slot formed in each of said segments for flowing fuelthrough said radial slot into said air tube to mix with the air therein.22. The combination as claimed in claim 15 including spaced tabs mountedon each of said splashplates and attached to each of said complementaryair tubes for supporting each of the splashplates in each of said airtubes whereby said splashplates are recessed in said air tubes toprevent the fuel impinging on said splashplates from spilling out of thecomplementary air tube.
 23. The combination as claimed in claim 15including a bracket interconnecting each of said splashplates to each ofsaid fuel nozzles for supporting the complementary splashplate in saidcomplementary air tube and each of said splashplate being recessed fromthe top of the complementary air tube to prevent the fuel impinging onsaid splashplate from spilling out of the complementary air tube. 24.The combination as claimed in claim 15 including a rearwardly facingface portion on said splashplate, said rearwardly facing face portionbeing configured to prevent the fuel/air mixture from recirculatingadjacent to the splashplate.
 25. The combination as claimed in claim 24wherein said configuration of said rearwardly facing face portion isdome shaped.
 26. The combination as claimed in claim 24 wherein theconfiguration of the rearwardly facing face portion of said splashplateis conically shaped.